The present invention relates to fuel cells and methods for manufacturing fuel cells.
As technology continues to advance, autonomous microsystems will likely be increasingly used for logging of measured values at poorly accessible or mobile sites. Such a microsystem typically includes an interconnection of, for example, sensors, actuators, a signal processor and a power supply. To output processed measured values, a microsystem may further include a transmitting unit or another interface for data output. Significant advancements have been made in the miniaturization and reduction of power consumption for sensor systems and actuator systems. Similar advancements, however, have not been made for the power supplies.
Typically, intelligent microsystems include integrated circuits that use Complementary Metal Oxide Semiconductor (CMOS) technology. Such integrated circuits typically include p-channel and n-channel Metal Oxide Semiconductor Field Effect Transistors (MOSFETs). By incorporating CMOS technology, however, materials and processes used for the intelligent microsystem must be CMOS-compatible, which is particularly relevant to CMOS processes that are monolithically performed on silicon chips. Furthermore, storage media should have a high energy density, components should be compatible with the environment, and the power supply should be able to be miniaturized and be cost effective.
The power supply for such autonomous microsystems can include batteries, storage batteries and micro fuel cells. Fuel cell systems have already become established as macroscopic energy systems. However, manufacturing fittings and guides having sufficient tolerances for mechanical components such as valves and pressure regulators, which include movable parts, has become increasingly more complicated due to needs for miniaturization. Attempts made so far at miniaturizing fuel cells are, therefore, limited to the fuel cell proper. Prior art methods include several approaches towards manufacturing PEM (Proton Exchange Membrane) fuel cells according to the silicon technology. Separate hydrogen storage units are made available, especially used, for power supply. In addition, direct methanol fuel cells are known, which are designed as passive systems, the oxidant methanol being supplied from a storage tank via capillary forces to the anode of the fuel cell. The CO2 gas bubbles formed during the reaction of the methanol are likewise removed using capillary forces.